Back to EveryPatent.com
United States Patent |
6,208,830
|
Takeda
|
March 27, 2001
|
Printing apparatus having improved paper cutting function
Abstract
A printer is provided which includes an image forming section for forming
an toner image on a surface of a photosensitive drum, a paper feeding unit
for feeding continuous paper along a feeding path to the surface of the
photosensitive drum, and a cutting unit for cutting the continuous paper
to provide cut sheets. The cutting unit is arranged to cut the continuous
paper after the leading portion of the continuous paper reaches the
surface of the photosensitive drum.
Inventors:
|
Takeda; Ikuo (Hyogo, JP)
|
Assignee:
|
Fujitsu Limited (Kawasaki, JP)
|
Appl. No.:
|
428538 |
Filed:
|
October 28, 1999 |
Foreign Application Priority Data
| Mar 23, 1999[JP] | 11-077909 |
Current U.S. Class: |
399/385 |
Intern'l Class: |
G03G 15//00; 7/; B41J 11//66 |
Field of Search: |
399/385,387,384
226/101
|
References Cited
U.S. Patent Documents
4248523 | Feb., 1981 | Doi et al. | 399/387.
|
5121867 | Jun., 1992 | Aoyama et al. | 226/101.
|
Foreign Patent Documents |
57-167281 | Oct., 1982 | JP.
| |
61-229770 | Oct., 1986 | JP.
| |
3-87274 | Apr., 1991 | JP.
| |
7-304220 | Nov., 1995 | JP.
| |
Primary Examiner: Grainger; Quana M.
Attorney, Agent or Firm: Armstrong, Westerman, Hattori, McLeland & Naughton
Claims
What is claimed is:
1. A printer with a photosensitive member comprising:
an image forming section for forming an toner image on a surface of the
photosensitive member;
continuous paper to which the toner image is transferred from the
photosensitive member;
a paper feeding unit for feeding the continuous paper along a feeding path
to the surface of the photosensitive member; and
a cutting unit for cutting the continuous paper to provide a cut sheet, the
cutting unit being arranged upstream from the photosensitive member;
wherein the paper feeding unit includes a first tractor arranged upstream
from the photosensitive member, and a second tractor arranged upstream
from the photosensitive member but downstream from the first tractor, each
of the first and second tractors including a rotating member provided with
a plurality of protrusions which are inserted into feed holes formed in
the continuous paper; and
wherein the cutting unit is arranged to cut the continuous paper between
the first tractor and the second tractor after a leading portion of the
continuous paper reaches the surface of the photosensitive member.
2. The printer according to claim 1, further comprising a detector for
detecting the leading portion of the continuous paper, the detector being
arranged upstream from the photosensitive member.
3. The printer according to claim 2, wherein the paper feeding unit is
arranged to advance the continuous paper by a predetermined amount after
the leading portion of the continuous paper is detected by the detector.
4. The printer according to claim 3, wherein the cutting unit is arranged
to cut the continuous paper after the continuous paper is advanced by said
predetermined amount.
5. The printer according to claim 1, wherein the feed holes are disposed
along a longitudinal edge of the continuous paper, the feed holes being
arranged at regular intervals.
6. The printer according to claim 1, wherein the rotating member is an
endless belt.
7. The printer according to claim 1, wherein the rotating member is a
roller.
8. The printer according to claim 1, wherein the continuous paper is
provided with cut lines arranged at regular intervals longitudinally of
the continuous paper, each of the cut lines including at least one cut.
9. The printer according to claim 8, wherein the cutting unit is arranged
to cut the continuous paper at the cut lines.
10. The printer according to claim 8, wherein the cutting unit is movable
along the feeding path of the continuous paper.
11. The printer according to claim 1, wherein the first tractor is arranged
to exert a resisting force on the continuous paper advancing along the
feeding path, so that the continuous paper is cut at a cut line.
12. The printer according to claim 11, wherein the second tractor is driven
at a higher rate than the first tractor for cutting the continuous paper.
13. The printer according to claim 8, wherein the cut is arranged to avoid
a portion of a longitudinal edge of the continuous paper.
14. The printer according to claim 8, wherein each of the cut lines
includes a relatively long cut and a relatively short cut which are
arranged to avoid a portion of a longitudinal edge of the continuous
paper.
15. A printer with a photosensitive member comprising:
an image forming section for forming a toner image on a surface of the
photosensitive member;
continuous paper to which the toner image is transferred from the
photosensitive member; and
a paper feeding unit for feeding the continuous paper along a feeding path
to the surface of the photosensitive member;
wherein the continuous paper is provided with cut lines arranged at regular
intervals longitudinally of the continuous paper, each of the cut lines
including at least one cut;
wherein the paper feeding unit includes a first tractor arranged upstream
from the photosensitive member, and a second tractor arranged upstream
from the photosensitive member but downstream from the first tractor, each
of the first and the second tractors including a rotating member provided
with a plurality of protrusions which are inserted into feed holes formed
in the continuous paper; and
wherein the second tractor is driven at a higher rate than the first
tractor for cutting the continuous paper at each cut line between the
first tractor and the second tractor after a leading portion of the
continuous paper reaches the surface of the photosensitive member.
16. A printer with a photosensitive member comprising:
an image forming section for forming a toner image on a surface of the
photosensitive member;
continuous paper to which the toner image is transferred from the
photosensitive member;
a paper feeding unit for feeding the continuous paper along a feeding path
to the surface of the photosensitive member; and
a cutting unit for cutting the continuous paper to provide a cut sheet, the
cutting unit being arranged upstream from the photosensitive member;
wherein the continuous paper is provided with cut lines arranged at regular
intervals longitudinally of the continuous paper, each of the cut lines
including at least one cut;
wherein the cutting unit is arranged to cut the continuous paper after a
leading portion of the continuous paper reaches the surface of the
photosensitive member; and
wherein the cutting unit is movable along the feeding path of the
continuous paper.
17. A printer with a photosensitive member comprising:
an image forming section for forming a toner image on a surface of the
photosensitive member;
continuous paper to which the toner image is transferred from the
photosensitive member;
a paper feeding unit for feeding the continuous paper along a feeding path
to the surface of the photosensitive member; and
a cutting unit for cutting the continuous paper to provide a cut sheet, the
cutting unit being arranged upstream from the photosensitive member;
wherein the cutting unit is arranged to cut the continuous paper after a
leading portion of the continuous paper reaches the surface of the
photosensitive member;
wherein the continuous paper is provided with cut lines arranged at regular
intervals longitudinally of the continuous paper, each of the cut lines
including at least one cut;
wherein the paper feeding unit includes a first tractor arranged upstream
from the photosensitive member, and a second tractor arranged downstream
from the first tractor, each of the first and the second tractors
including a rotating member provided with a plurality of protrusions which
are inserted into feed holes formed in the continuous paper; and
wherein the first tractor is arranged to exert a resisting force on the
continuous paper advancing along the feeding path, so that the continuous
paper is cut at each cut line.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing apparatus for printing images
using, a photosensitive unit such as a photosensitive drum. In particular,
the present invention relates to a printer incorporating a paper-cutting
mechanism to cut continuous recording paper into separate cut sheets for
printing desired images on these cut sheets.
2. Description of the Related Art
A conventional printer of the above type is disclosed in
JP-A-7(1995)-304220 for example. As shown in FIG. 7 of the accompanying
drawings of the present application, the conventional printer has an image
forming section provided with a photosensitive belt 90, a transfer unit 91
and a fixation unit 92. The printer also includes a paper holder 93 for
accommodating a paper roll R. Continuous recording paper 94 is paid out
from the paper roll R to be brought into contact with the photosensitive
belt 90 by a plurality of feed rollers 95.
In the conventional printer, use is made of a sensor 96 and a cutter 97,
each of which is arranged at a suitable location along the feeding path of
the continuous paper 94. The sensor 96 is provided for detecting the
passage of the continuous paper 94, while the cutter 97 is provided for
cutting the continuous paper 94. More specifically, the sensor 96 is
arranged to detect the passage of the leading portion of the continuous
paper 94. Upon such detection, the continuous paper 94 is advanced a
predetermined distance toward the photosensitive belt 90. Then, after the
continuous paper 94 has been thus moved, the cutter 97 is operated to cut
the continuous paper 94 to provide a cut sheet of a predetermined size.
The advantages of the conventional printer are as follows. Firstly, the
recording paper 94 is a single elongated sheet when it is drawn out from
the paper holder 93. Thus, the recording paper 94 will not suffer the
problem of "double feed" which is liable to occur when initially separate
cut sheets are used in place of the continuous paper 94.
Secondly, the continuous paper 94 is not allowed to maintain its continuous
form but is cut into separate sheets by the cutter 97 arranged upstream
from the photosensitive belt 90. With such an arrangement, the mechanisms
of components arranged behind (i.e., downstream from) the photosensitive
belt 90 are advantageously simplified, as in a specialized printer which
is designed to deal with cut sheets only. This advantage can be better
understood by considering the following case.
If the continuous paper 94 is not to be cut into separate cut sheets at
all, additional devices, which would otherwise be unnecessary, may be
required. The additional devices may include devices to detach the
photosensitive belt 90 and the fixation unit 92 from the continuous paper
94 when the printing operation should be halted temporarily. Such
detachment is needed for protecting the belt 90 from possible mechanical
damage inflicted by the continuous paper 94, and for protecting the paper
94 from possible thermal damage inflicted by the fixation unit 92. The
additional devices may also include a folding device for the continuous
paper 94. The folding device may be disposed at the end of the feeding
path for alternately folding the continuous paper 94, so that the
discharged paper 94 is neatly accommodated in a stacker.
Though the conventional printer possesses the above advantages, it has been
found disadvantageous in the following points.
In the conventional printer, the continuous paper 94 is cut into a separate
sheet before the leading portion of the continuous paper 94 comes into
contact with the photosensitive belt 90. Thus, the cut sheet separated
from the continuous paper 94 needs to be transferred a certain distance
until it comes into contact with the photosensitive belt 90. In this
manner, the cut sheet tends to be improperly oriented (skewed for example)
during the transfer to the photosensitive belt 90. When such improper
transfer occurs, the cut sheet may fail to come into square contact with
the photosensitive belt 90. Consequently, the printing operation may be
started at an unintended portion of the cut sheet, and the resulting image
printed on the cut sheet may unfavorably be slanted.
SUMMARY OF THE INVENTION
The present invention has been proposed under the above circumstances, and
its objective is to eliminate, or at least reduce, the problems described
above.
For attaining the above objective, the present invention takes the
following technical measures.
According to the present invention, there is provided a printer with a
photosensitive member comprising:
an image forming section for forming an toner image on a surface of the
photosensitive member;
continuous paper to which the toner image is transferred from the
photosensitive member;
a paper feeding unit for feeding the continuous paper along a feeding path
to the surface of the photosensitive member; and
a cutting unit for cutting the continuous paper to provide a cut sheet, the
cutting unit being arranged upstream from the photosensitive member;
wherein the cutting unit is arranged to cut the continuous paper after a
leading portion of the continuous paper reaches the surface of the
photosensitive member.
With such an arrangement, when the continuous paper is cut by the cutting
unit, the leading portion of the continuous paper has already arrived at
the surface of the photosensitive member. Thus, as opposed to the
conventional printer, the cut sheet separated from the continuous paper
does not need to be transferred to the photosensitive member. In this
manner, the positioning of the cut sheet relative to the photosensitive
member can be accurately performed. As a result, it is possible to reduce,
or even eliminate, the positional deviation of the image to be printed on
the cut sheet.
According to a preferred embodiment, the printer may further comprise a
detector for detecting the leading portion of the continuous paper,
wherein the detector is arranged upstream from the photosensitive member.
With such a printer provided, the paper feeding unit may be arranged to
advance the continuous paper by a predetermined amount after the leading
portion of the continuous paper is detected by the detector.
Further, the cutting unit may be arranged to cut the continuous paper after
the continuous paper is advanced by said predetermined amount.
Preferably, the paper feeding unit of the printer may comprise at least one
tractor including a rotating member provided with a plurality of
protrusions which are inserted into feed holes formed in the continuous
paper.
With such an arrangement, the problem of possible slip or positional
deviation of the continuous paper with respect to the paper feeding unit
can be overcome.
Preferably, the feed holes may be disposed along a longitudinal edge of the
continuous paper at regular intervals.
Preferably, the rotating member may be an endless belt or a roller.
Preferably, the continuous paper may be provided with cut lines arranged at
regular intervals longitudinally of the continuous paper, and each of the
cut lines may include at least one cut.
The cutting unit may be arranged to cut the continuous paper at the cut
lines.
Preferably, the cutting unit may be movable along the feeding path of the
continuous paper. With such an arrangement, by adjusting the fixing
position of the cutting unit along the feeding path, the length of the cut
sheet separated from the continuous paper can be varied.
Advantageously, the paper feeding unit may include an additional tractor
arranged downstream from the above-mentioned one tractor.
Further, the above-mentioned one tractor may preferably be arranged to
exert a resisting force on the continuous paper advancing along the
feeding path, so that the continuous paper is cut at a cut line.
With such an arrangement, the paper feeding unit can achieve two functions,
that is, the paper feeding function and the paper cutting function. In
this situation, there is no need to render the printer to incorporate a
specialized cutting means for cutting the continuous paper, whereby the
construction of the printer can be simplified.
When the paper feeding unit is to be used for cutting the continuous paper,
the additional tractor may be driven at a higher rate than the
above-mentioned one tractor is. In this manner, a suitable tension is
generated in a portion of the continuous paper between the two tractors,
the continuous paper will be cut at the cut line.
Preferably, the cut of the cut line may be arranged to avoid a portion of a
longitudinal edge of the continuous paper. With such an arrangement, the
pulling force from the paper feeding unit is properly transferred to the
continuous paper.
Preferably, each of the cut lines may include a relatively long cut and a
relatively short cut which are arranged to avoid a portion of a
longitudinal edge of the continuous paper.
Other objects, features and advantages of the present invention will become
clearer from the following detailed description given with reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a schematic view showing an example of printer according to the
present invention;
FIG. 2 is a front view showing a principal portion of an example of
continuous paper;
FIGS. 3 and 4 are schematic views illustrating how the printer of FIG. 1
operates;
FIGS. 5A and 5B are schematic views illustrating how a cutting mechanism
works;
FIGS. 6A-6C are schematic views showing various types of continuous paper;
and
FIG. 7 is a schematic view showing an example of conventional printer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the present invention will be described below
with reference to the accompanying drawings.
FIG. 1 is a schematic view showing an example of a printer according to a
preferred embodiment of the present invention. FIG. 2 is a front view
showing a principal portion of an example of continuous paper. FIGS. 3 and
4 are schematic views illustrating how the printer of FIG. 1 is operated.
For convenience of explanation, reference is first made to FIG. 2 which
illustrates continuous paper 2 used for the printer of the preferred
embodiment. As illustrated, the continuous paper 2 has an elongated
configuration, extending in an N1-direction. The continuous paper 2 is
formed with a plurality of feed holes 20 and a plurality of cut lines 21.
The feed holes 20 are divided into two rows, one of which extends along a
longitudinal edge 22a of the continuous paper 2, while the other row
extends along the opposite longitudinal edge 22b. In each row, the feed
holes 20 are arranged at regular intervals.
The plurality of cut lines 21 are arranged at predetermined intervals as
viewed longitudinally of the continuous paper 2. Each of the cut lines 21
includes two relatively long straight cuts 21a and a plurality of
relatively short straight cuts 21b. Between the cuts 21a and 21b are
provided connecting regions Sa or connecting regions Sb. The first
connecting regions Sa are part of the longitudinal edges 22a, 22b of the
continuous paper 2, whereas the second connecting regions Sb are part of
the widthwise central portion of the continuous paper 2. The connecting
regions Sa and Sb have small lengths (as viewed widthwise of the
continuous paper 2). Thus, the sum of the lengths of the cuts 21a, 21b is
nearly equal to the width of the continuous paper 2.
The continuous paper 2 shown in FIG. 2 is depicted as a plain sheet.
However, the illustrated paper is merely an example and its arrangement
may be modified. For instance, the continuous paper 2 may be provided with
reference lines (such as rules), characters, figures or patterns, for
example. Initially the continuous paper 2 is alternatively folded at the
cut lines 21 and accommodated in the paper holder 3 (see FIG. 1).
As shown in FIG. 1, the printer A according to the present invention is
provided with an image forming section 1 for producing images by an
electrophotographic process (EP process), a feeding unit 4 for causing the
continuous paper 2 to be transferred along a feeding path from the paper
holder 3 to the image forming section 1, and a cutting unit 5 for cutting
the continuous paper 2.
The image forming section 1 of the printer A is basically similar to that
of a conventionally available printer arranged to print images by an EP
process. Specifically, the image forming section 1 is provided with a
rotatable photosensitive drum 10. Around the photosensitive drum 10 are a
charge unit 11, a laser beam emitting unit 12 for optically writing
images, a developing unit 13, a cleaner 15, and a static eliminating LED
(light-emitting diode) 16.
The printer A also includes an image transfer unit 14 adjacent to the
surface of the photosensitive drum 10, and a fixation unit 17 arranged
downstream from the photosensitive drum 10. The fixation unit 17 is
provided with a pair of heater rollers.
In the image forming section 1, a desired image (latent image) is
electrostatically composed on the surface of the photosensitive drum 10,
and this image is developed by toner supplied from the developing unit 13.
Then, when a recording paper sheet is brought between the drum 10 and the
image transfer unit 14, the toner-developed image is transferred from the
drum 10 to the paper sheet.
The transferred image on the paper sheet is heated by the fixation unit 17
to be fixed to the sheet. Finally, the paper sheet is discharged from a
discharge opening 60, and received by a stacker 61 arranged downstream
from the fixation unit 17.
The feeding unit 4 includes first and second tractors 41A, 41B, for moving
the continuous paper 2 toward the photosensitive drum 10 along the feeding
path. The feeding unit 4 also includes a suitable number of guide rollers
42 (only one is shown in FIG. 1) and guide plates 44. These rollers 42 and
plates 44 define the feeding path of the continuous paper 2.
Each of the first and the second tractors 41A, 41B is provided with a pair
of endless belts 41a (only one is shown in FIG. 1) and a pair of rollers
41b, 41c. The endless belt 41a passes around the rollers 41b, 41c. Thus,
when the rollers 41b, 41c are rotated, the endless belt 41a is moved
accordingly for advancing the continuous paper 2 along the feeding path.
For achieving a proper paper feeding operation, the endless belt 41a is
provided with a plurality of protrusions that are sequentially brought
into engagement with the feed holes 20 of the continuous paper 2. In this
manner, the continuous paper 2 is unfailingly advanced along the feeding
path by the first and the second tractors 41A, 41B.
The cutting unit 5 is disposed between the first tractor 41A and the second
tractor 41B for cutting the continuous paper 2. As shown in FIG. 1, the
cutting unit 5 includes an upper plate 50a and a lower plate 50b which are
vertically spaced from each other, with the feeding path extending
therebetween.
In the illustrated embodiment, the upper and lower plates 50a, 50b are both
movable toward and away from each other. (Alternatively, only one of them
may be arranged to move.) The cutting edges of the respective plates 50a,
50b (i.e., the lower edge of the upper plate 50a and the upper edge of the
lower plate 50b) are blunt. Nevertheless, as will be described later in
detail, the two plates 50a, 50b can properly cut the continuous paper 2 at
the respective cut lines 21. Preferably, the cutting edges of the
respective plates 50a, 50b may be sharp so that the continuous paper 2 is
properly cut even if the cut lines 21 are not provided.
As indicated by two-headed arrow N2 in FIG. 1, the position of the upper
and lower plates 50a, 50b is adjustable to a limited extent along the
feeding path. With such an arrangement, it is possible to vary the
longitudinal length of a cut sheet to be separated from the continuous
paper 2 by the cutting unit 5. The reciprocative range of the plates 50a,
50b is suitably limited for preventing the plates 50a, 50b from
interfering with the first and second tractors 41A, 41B.
Still referring to FIG. 1, a sensor 43 is provided at a point adjacent to
the feeding path and upstream from the photosensitive drum 10. The sensor
43 serves to detect, at a point P2, the passage of the leading portion of
the continuous paper 2 fed by the feeding unit 4. Upon detection of the
leading portion of the paper 2, the sensor 43 outputs corresponding
detection signals.
Based on the detection signal from the sensor 43, the first and the second
tractors 41A, 41B move the continuous paper 2 forward so that the leading
portion of the paper 2 is brought to a point P1 on the surface of the
photosensitive drum 10. (As illustrated in FIG. 1, the point P1 is in
facing relation to the image transfer unit 14.)
When the leading portion of the paper 2 comes to the point P1, the cutting
unit 5 is operated to cut the paper 2. The operation of the cutting unit 5
is controlled by non-illustrated controlling means incorporated in the
printer A. Typically, the controlling means may be a microcomputer
including a CPU, memories, and so forth, which are accommodated in a
housing 62 of the printer A.
In the illustrated embodiment, use is made of the first and second tractors
41A, 41B for feeding the continuous paper 2. Since the endless belts 41c
are provided with protrusions to be inserted into the feed holes 20 of the
continuous paper 2, the two tractors 41A, 41B can properly advance the
continuous paper 2 along the feeding path, whereby no slip and no
positional deviation will occur between the continuous paper 2 and the
tractors 41A, 41B.
From the above fact, it can be known that the displacement of the
continuous paper 2 along the feeding path is in exact correspondence with
the feeding motion of the endless belts 41c. Thus, the non-illustrated
controlling means can determine, by monitoring the state of the tractors
41A and 41B in operation, what position the leading portion of the paper 2
is brought to at any given moment. Consequently, the controlling means can
calculate when the leading portion of the continuous paper 2 arrives at
the point P1 on the photosensitive drum 10.
In view of the above, it is possible to omit the sensor 43 provided for
detecting the passage of the paper 2. If the sensor 43 may remain, it can
be used for detecting positional deviation (not the passage) of the
continuous paper 2 which may occur, for example, when the paper 2 is
unduly torn.
When use is made of continuous paper formed with no feed holes, ordinary
feed rollers (instead of the tractors 41A, 41B) may be used for feeding
the continuous paper. Disadvantageously, the feed rollers may slip on the
continuous paper, thereby failing to properly feed the continuous paper.
This means that the non-illustrated controlling means may fail to
calculate the correct position of the leading portion of the continuous
paper only by monitoring the operational state of the feed rollers. In
such an instance, the sensor 43 for detecting the passage of the
continuous paper may be of great help.
The operation and advantages of the printer A will now be described below.
First, referring to FIG. 1, the first and the second tractors 41A, 41B are
actuated for feeding the continuous paper 2 from the paper holder 3 to the
photosensitive drum 10. This feeding operation with the continuous paper 2
is performed properly, as previously described, since the protrusions of
the endless belts 41a of the first and the second tractors 41A, 41B are
sequentially brought into engagement with the feed holes 20 formed in the
continuous paper 2. Thus, the continuous paper 2 is caused to move an
exact distance corresponding to the rotational movement of the rollers
41b, 41c of the tractors 41A, 41B.
Referring to FIG. 2, the left-hand longitudinal edge 22a is not completely
separated by the cut line 21. More specifically, the left-hand short cut
21b and the left-hand long cut 21a of the cut line 21 are spaced from each
other by a small distance, thereby providing a connecting region Sa.
Similarly, the right-hand longitudinal edge 22b contains another
connecting region Sa. Because of these connecting regions Sa, the
continuous paper 2 is provided with an appropriate strength to withstand
the tension exerted on the paper 2 during the transferring operation.
Thus, the driving force generated by the first and second tractors 41A,
41B is properly transmitted to the continuous paper 2 without causing the
continuous paper 2 to be torn prematurely at the cut lines 21. This
advantage is enhanced by the generally central connecting regions Sb
provided between the relatively long cuts 21a and the relatively short cut
21b.
When the leading portion of the continuous paper 2 arrives at the
predetermined point P1 on the photosensitive drum 10, the cutting unit 5
is actuated to cut the continuous paper 2. To this end, the cutting unit 5
is disposed at a suitable position along the feeding path, so that the two
plates 50a, 50b can come into contact with the cut line 21 of the paper 2
when the leading portion of the paper 2 reaches the point P1. With such an
arrangement, the continuous paper 2 is properly cut at the cut line 21 by
the cutting unit 5.
In this connection, it should be appreciated that the cut line 21 includes
the relatively long cuts 21a extending widthwise of the continuous paper
2. With such an arrangement, the continuous paper 2 pulled along the
feeding path with a suitable tension can readily be cut at the cut line 21
when the plates 50a, 50b only slightly engage with the continuous paper 2.
This means that the cutting force needed for cutting the continuous paper
2 is rendered advantageously small. Thus, the continuous paper 2 is
prevented from being unduly pulled backward (i.e., upstream of the feeding
path) when the plates 50a, 50b are brought into contact with the paper 2
for cutting the paper.
By preventing the backward deviation of the continuous paper 2 in the above
manner, the leading portion of the resulting cut sheet 2A can
substantially remain at the point P1 of the photosensitive drum 10. For
enabling more reliable prevention of the positional deviation of the cut
sheet 2A from the point P1, use may be made of pinch rollers (not shown)
to press the cut sheet 2A therebetween. Such pinch rollers may be arranged
at suitable locations upstream from the photosensitive drum 10.
While the cutting operation is being performed, the continuous paper 2 may
be halted for a while. Alternatively, the paper 2 may continue to be
advanced along the feeding path during the cutting operation.
Some of the technically significant features of the above embodiment in
terms of accurate image transfer may be as follows. Firstly, the leading
portion of the cut sheet 2A is initially held in contact with the
photosensitive drum 10. (In other words, the cut sheet 2A does not need to
be additionally moved along the feeding path for coming into engagement
with the photosensitive drum 10 after the cut sheet 2A is obtained from
the continuous paper 2.) Secondly, the positioning of the leading portion
of the cut sheet 2A relative to the photosensitive drum 10 is performed
accurately during the feeding process of the continuous paper 2. Thirdly,
the leading portion of the cut sheet 2A can electrostatically cling to the
surface of the photosensitive drum 10 which is electrostatically charged.
Because of the above features, the toner image produced on the
photosensitive drum 10 is transferred onto the predetermined region in the
cut sheet 2A with excellent positional accuracy. Thus, the resulting image
printed on the cut sheet 2A will appear without positional deviation. when
no printing operation is to be performed immediately after the
above-stated printing operation ("first printing operation" below) with
respect to the cut sheet 2A, the first tractor 41A may be turned off after
the cut sheet 2A is separated from the continuous paper 2. In this case,
the continuous paper 2 does not extend beyond the cutting unit 5, as shown
in FIG. 4.
Alternatively, the first and the second tractors 41A, 41B may be actuated
for a while after the cut sheet 2A is separated from the continuous paper
2. In this case, the leading portion of the continuous paper 2 may be
brought to a point located upstream from, but close to, the photosensitive
drum 10. When the leading portion of the paper 2 reaches the particular
point, the first and the second tractors 41A, 41B are turned off.
When another printing operation is to be performed successively after the
first printing operation, the continuous paper 2 may continue to be moved
toward the photosensitive drum 2 even after the cut sheet 2A is separated
from the continuous paper 2. Thus, while the first printing operation is
being performed with the cut sheet 2A, the continuous paper 2 may still be
advancing along the feeding path. Then, in a certain period of time,
another cut sheet is separated from the continuous paper 2, and a desired
image is to be printed on this cut sheet.
In place of the continuous paper 2 used in the illustrated embodiment, use
may be made of another type of continuous paper which may also be provided
with suitable cut lines. The intervals at which the cut lines of the new
continuous paper are arranged may be different from those of the
continuous paper 2. In such an instance, when the leading portion of the
new continuous paper is brought to the point P1 on the photosensitive drum
10, the cut line of the new continuous paper may be located at a position
different from where the cut line 21 of the above-described continuous
paper 2 was located.
In this connection, it should be appreciated that the cutting unit 5 is
adjustable in position along the feeding path, as indicated by the arrow
N2 in FIG. 1. Thus, even when the cut line is positionally shifted to a
certain extent along the feeding path, the cutting unit 5 can properly cut
the new continuous paper at the cut line. In this manner, the illustrated
printer A of the present invention can deal with various types of
continuous paper having cut lines arranged at various intervals.
In the preferred embodiment described above, the continuous paper 2 is cut
into a separate sheet when the leading portion of the paper 2 comes into
contact with the surface of the photosensitive drum 10. The present
invention, however, is not limited to this embodiment. For instance, the
continuous paper 2 may be cut after the leading portion of the paper 2 has
reached the drum 10 and is further advanced to a certain extent. In this
connection, more detailed description will be given below with reference
to FIG. 1.
FIG. 1 illustrates an instance where the cutting unit 5 is set at a
position corresponding to the intervals at which the cut lines 21 (FIG. 2)
of the paper 2 are arranged. It is now supposed that in place of the
continuous paper 2 ("first continuous paper" below), use is made of a
different type of continuous paper ("second continuous paper" below) whose
cut lines are arranged at certain intervals. Here, the distance between
adjacent cut lines of the second continuous paper is greater than that of
the first continuous paper. It is also supposed that the cutting unit 5 is
not to be moved from the initial position along the feeding path.
In the above instance, when the leading portion of the second continuous
paper arrives at the point P1 on the photosensitive drum 10, a relevant
cut line is yet located upstream from the paired plates 50a, 50b of the
cutting unit 5. Thus, in order to properly cut the second continuous
paper, it is necessary to further advance the paper along the feeding path
until the relevant cut line comes between the upper and the lower plates
50a, 50b of the cutting unit 5. When the cut line is brought to this
particular point, the cutting unit 5 is operated to cut the second
continuous paper. At this stage, the image-printing with respect to the
leading portion of the second continuous paper may already be started.
In the manner described above, there is no need to adjust the position of
the cutting unit 5 whenever one continuous paper is to be replaced with
another continuous paper.
For cutting the continuous paper, it is possible to use various kinds of
cutting tools. For instance, a pair of blades with sharp cutting edges may
preferably be used in some applications. In other applications, a circular
rotary cutter which is movable across (widthwise of) the continuous paper
may be useful.
Still further, it is possible to cut the continuous paper without using any
one of the cutting units described above. To this end, use may be made of
the first and the second tractors 41A, 41B, as shown in FIGS. 5A-5B.
Specifically, it is supposed that the first and the second tractors 41A,
41B are initially operated to feed the continuous paper 2 at a constant
speed of V (see FIG. 5A). Then, as shown in FIG. 5B, the speed of the
first tractor 41A (which is located upstream from the second tractor 41B)
is reduced to a lower speed Va (which may include zero). In this manner, a
tension is exerted on the continuous paper 2 to pull the paper
longitudinally thereof, so that the continuous paper 2 will be separated
at the cut line 21 (see FIG. 2) located between the two tractors 41A, 41B.
According to the present invention, as stated above, it is not always
necessary to provide a cutting device which is exclusively used for
cutting the continuous paper. Without such a device, other components of
the printer may be used both for cutting the continuous paper and for
performing another function.
Reference is now made to FIGS. 6A-6C illustrating various types of
continuous paper (roll-type continuous paper) which are usable for the
printer of the present invention. These continuous papers are different
from the continuous paper 2 shown FIG. 2.
Specifically, the continuous paper 2a shown in FIG. 6A is formed with feed
holes 20 (each of which has a rectangular configuration) but not with cut
lines. The continuous paper 2b shown in FIG. 6B has no feed holes but is
formed with cut lines (perforations) 21. The continuous paper 2c shown in
FIG. 6C is not formed with feed holes nor cut lines. Instead of the
continuous papers 2a-2c described above, a non-roll type of continuous
paper may be used for a printer of the present invention.
Each component or element of the printer (particularly, the cutting unit
and the feeding unit) may suitably be arranged so that the printer can
deal with various kinds of continuous paper. For instance, when use is
made of continuous paper formed with no feed holes, the printer may
incorporate rotatable rollers (instead of tractors as shown in FIG. 1) for
feeding the continuous paper.
In the illustrated embodiment, the endless belts 41a provided with
protrusions are used for the first and the second tractors 41A, 41B. In
place of these endless belts, the tractors 41A, 41B may be provided with
rotatable rollers provided with protrusions for engaging with the
continuous paper.
Further, in the illustrated embodiment, the photosensitive drum 10 is used
a photosensitive unit. Alternatively, use may be made of a photosensitive
belt as shown in FIG. 7 (prior art). The specific design of the image
forming section including such a photosensitive unit is not limited to the
illustrated example but may be varied in many ways.
According to the present invention, the continuous paper is cut into a
separate cut sheet after the leading portion of the continuous paper comes
into contact with the surface of the photosensitive drum. In this manner,
since the cut sheet does not need to be additionally advanced to engage
with the photosensitive drum, the leading portion of the cut sheet is
accurately positioned relative to the photosensitive drum. Thus, as
compared with the conventional printer (in which the continuous paper is
cut into a separate cut sheet before the leading portion of the paper
reaches the photosensitive belt), the desired image is properly printed on
the cut sheet without positional deviation.
The present invention being thus described, it is obvious that the same may
be varied in many other ways. Such variations are not to be regarded as a
departure from the spirit and scope of the present invention, and all such
modifications as would be obvious to those skilled in the art are intended
to be included within the scope of the following claims.
Top